In a system such as a time-division multiple access TDMA cellular radiotelephone, the antenna is alternately to be used at the output of the transmitting circuit or at the input of the receiving circuit. It is thus necessary to isolate these two circuits from each other. Indeed, if the transmitting circuit is not correctly isolated, a significant part of the transmitting power flows into the receiving circuit which is not used at that moment; furthermore, a part of the transmitting power is sent back to its source without even having reached the antenna. Similarly, on the receiving end, a poor isolation relative to the transmitting circuit would lead to losses owing to dissipation or mismatches.
Currently, electrostatic relays such as described, for example, in the document U.S. Pat. No. 5,578,976, are not fast enough and this type of antenna switching device can only be realized for obtaining the desired useful life and rapidity by means of semiconductors such as a PIN diode. But, with such an element, the losses are at least 1 dB because of the series resistance and the current limit imposed thereon (of the order of 1 mA). On the other hand, the compression point of such a switching device is not very high and it thus has a poor linearity.